Anaerobic digestion of brewers' spent grain in a novel plug flow reactor system

Abstract

Beer brewing generates large amounts of spent grain which is currently used mostly as an animal feed. Anaerobic digestion offers an opportunity to generate methane from this low-value by-product, potentially increasing the value of this waste and diversifying its usage streams. A novel modified plug-flow UASB dual reactor was proposed which allows for different hydraulic and solids retention times, which decreases by-product inhibition in the anaerobic digestion process. The effect of by-product inhibition as an important factor in anaerobic systems was tested. Also, an analysis of other potential options for downstream uses of the digestate liquid and digested spent grain are discussed.